The Effects Of Too Much High Intensity Interval Training May Surprise You

If you have ever tried to maximize your benefits from a workout in a time-efficient way, you've probably come across high intensity interval training — commonly known as a HIIT workout.

Healthline says that high-intensity interval training is a quick workout, usually under a half hour in length, that cycles from high intensity exercise to low intensity periods of recovery. For example, you might run up a hill for 30 seconds — the high intensity exercise — and then walk back down — the low intensity recovery period — and start again for 10 repetitions (via Men's Health). According to Healthline, high intensity interval training might provide some added health benefits too, like gaining muscle or losing fat.

Medical News Today says that high intensity interval training gained traction in the public because it offered a fast and functional way to stay in shape. According to a 2022 study published in the American College of Sports Medicine's Health and Fitness Journal, high intensity interval training was a top five fitness trend in the world for several years. However, the exercise program fell out of the top five for the first time in 2022, when it dropped to number seven. It could have something to do with overtraining. Here's what you need to know about the potentially negative health effects of too much high intensity interval training.

There is such a thing as too much exercise

As early as 2016, Men's Health warned that high intensity interval training should be done sparingly because of how stressful it is. Some physical trainers cautioned that too much intense exercise could oversaturate the body with stress hormones like cortisol (per Insider). A 2021 study published in the Scandinavian Journal of Medicine and Science in Sports found that cortisol levels increase significantly right after a high intensity interval training workout, then drop below baseline before returning to baseline after 24 hours. But what happens when you push the limits with high intensity training?

A 2021 study published in the journal Cell Metabolism found that excessive exercise — 152 minutes of high intensity interval training per week — led to "negative effects on metabolic health and adaptation of physical performance." Notably, the participants showed cellular dysfunction in mitochondria — commonly referred to as the powerhouse of the cell. In short, too much high intensity interval training can drain you of energy, which may negatively affect your health, metabolism, and performance (via Insider).

Healthline says that the most common symptoms of overtraining range from chronic fatigue and altered sleep to a lack of motivation. If you feel too tired to train and don't have the strength, consider taking a break from high intensity interval training. Remember not to push yourself further than your body can handle.